This patch implements the `llvm.loop.estimated_trip_count` metadata
discussed in [[RFC] Fix Loop Transformations to Preserve Block
Frequencies](https://discourse.llvm.org/t/rfc-fix-loop-transformations-to-preserve-block-frequencies/85785).
As [suggested in the RFC
comments](https://discourse.llvm.org/t/rfc-fix-loop-transformations-to-preserve-block-frequencies/85785/4),
it adds the new metadata to all loops at the time of profile ingestion
and estimates each trip count from the loop's `branch_weights` metadata.
As [suggested in the PR #128785
review](https://github.com/llvm/llvm-project/pull/128785#discussion_r2151091036),
it does so via a new `PGOEstimateTripCountsPass` pass, which creates the
new metadata for each loop but omits the value if it cannot estimate a
trip count due to the loop's form.
An important observation not previously discussed is that
`PGOEstimateTripCountsPass` *often* cannot estimate a loop's trip count,
but later passes can sometimes transform the loop in a way that makes it
possible. Currently, such passes do not necessarily update the metadata,
but eventually that should be fixed. Until then, if the new metadata has
no value, `llvm::getLoopEstimatedTripCount` disregards it and tries
again to estimate the trip count from the loop's current
`branch_weights` metadata.
Adding 2 passes, one to inject `MD_prof` and one to check its presence. A subsequent patch will add these (similar to debugify) to `opt` (and, eventually, a variant of this, to `llc`)
Tracking issue: #147390
This will be useful for testing the set of calls for different systems,
and eventually the product of context specific modifiers applied. In
the future we should also know the type signatures, and be able to
emit the correct one.
Expose the FatLTO pipeline via `-passes="fatlto-pre-link<Ox>"`, similar
to all the other optimization pipelines. This is to allow reproducing it
outside clang. (Possibly also useful for C API users.)
Most of the recent development on the MemProfiler has been on the Use part. The instrumentation has been quite stable for a while. As the complexity of the use grows (with undrifting, diagnostics etc) I figured it would be good to separate these two implementations.
These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
Introduce a fresh analysis for recognizing polynomial hashes, with the
rationale that several targets have specific instructions to optimize
things like CRC and GHASH (eg. X86 and RISC-V crypto extension). We
limit the scope to polynomial hashes computed in a Galois field of
characteristic 2, since this class of operations can also be optimized
in the absence of target-specific instructions to use a lookup table.
At the moment, we only recognize the CRC algorithm.
RFC:
https://discourse.llvm.org/t/rfc-new-analysis-for-polynomial-hash-recognition/86268
When we enable EVL-based loop vectorization w/ predicated tail-folding,
each vectorized loop has effectively two induction variables: one
calculates the step using (VF x vscale) and the other one increases the
IV by values returned from experiment.get.vector.length. The former,
also known as canonical IV, is more favorable for analyses as it's
"countable" in the sense of SCEV; the latter (EVL-based IV), however, is
more favorable to codegen, at least for those that support scalable
vectors like AArch64 SVE and RISC-V.
The idea is that we use canonical IV all the way until the end of all
vectorizers, where we replace it with EVL-based IV using EVLIVSimplify
introduced here. Such that we can have the best from both worlds.
This Pass is enabled by default in RISC-V. However, since we haven't
really vectorize loops with predicate tail-folding by default, this Pass
is no-op at this moment.
This adds a GISelValueTrackingPrinterPass that can print the known bits
and sign bit of each def in a function. It is built on the new pass
manager and so adds a NPM GISelValueTrackingAnalysis, renaming the older
class to GISelValueTrackingAnalysisLegacy.
The first 2 functions from the AArch64GISelMITest are ported over to an
mir test to show it working. It also runs successfully on all files in
llvm/test/CodeGen/AArch64/GlobalISel/*.mir that are not invalid. It can
hopefully be used to test GlobalISel known bits analysis more directly
in common cases, without jumping through the hoops that the C++ tests
requires.
/llvm-project/llvm/lib/Passes/PassBuilder.cpp:1508:2:
error: extra ';' outside of a function is incompatible with C++98 [-Werror,-Wc++98-compat-extra-semi]
1508 | };
| ^
1 error generated.
- Add new pass manager version of `MachineUniformityAnalysis `.
- Query `TargetTransformInfo` in new pass manager version.
- Use `printAsOperand` when printing machine function name
Not sure why the "fold-all" option naming didn't match the
variable "FoldPreOutputs", but I've preserved the difference.
More annoyingly, the pass name "normalize" does not match the pass
name IRNormalizer and should probably be fixed one way or the other.
Also the existing test coverage for the flags is lacking. I've added
a test that shows they parse, but we should have tests that they
do something.
This patch does two things:
1. It implements an ephemeral values cache analysis pass that collects the ephemeral values of a function and caches them for fast lookups. The collection of the ephemeral values is done lazily when the user calls `EphemeralValuesCache::ephValues()`.
2. It adds caching of ephemeral values using the `EphemeralValuesCache` to speed up `CallAnalyzer::analyze()`. Without caching this can take a long time to run in cases where the function contains a large number of `@llvm.assume()` calls and a large number of callsites. The time is spent in `collectEphemeralvalues()`.
For the NewPM, the merge-const option was assigned to an unused
option field. Assign it to the correct one. The merge-const-aggressive
option was not supported -- and invalid options were silently ignored.
Accept it and error on invalid options.
For the LegacyPM, the corresponding cl::opt options were ignored when
called via opt rather than llc.
This is meant as a preparation for PR #130988 "[AMDGPU] Implement IR
expansion for frem instruction" which implements the expansion of
another instruction in this pass. The more general name seems more
appropriate given this change and quite reasonable even without it.
EnableTailMerge is false by default and is handled by the pass builder.
Passes are independent of target pipeline options.
This completes the generic `MachineLateOptimization` passes for the NPM
pipeline.
